Best hot water heating system for off-grid year-round cabin (zone 4c)

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Best hot water heating system for off-grid year-round cabin (zone 4c)

Hello,

Newbie here so please be gentle!

My husband and I are currently renovating a 1950's 1 1/2 story 750 sq. ft. cabin in coastal BC for use on most weekends and holidays. It's off-grid, but has access to the community's diesel-powered 15 kW generator. The fuel bills for electricity are enormous and I doubt the generator will be around 10 years from now, so I'm trying to minimize electricity use when looking at what to do with the cabin.

At the moment, our hot water heater system consists of an indirect 20 gallon storage tank (in the bathroom), heated by a coil in the oil stove (in the kitchen next door) using thermosiphoning. The oil stove is a McClary Charm converted from wood to an oil pot-burner at the factory. We've got it going and are experimenting to see how much it burns - so far it's about 1/2 a jerry can (10L) per day. With stove oil at $1.47/L, not cheap, efficient or environmentally-friendly! And while we haven't got to use the shower yet, apparently when my parents lived there in the 70's, they could each have one short shower per day - one in the morning and one in the evening.

I've thought of just swapping out the oil stove for an Esse Ironheart wood cookstove with boiler, but at 800 lbs for the unit, I don't think the floor would support it (the cabin is suspended on log skids). And I'm not sure how cold the cabin would get overnight because I think the fire would die down (did I mention that the insulation is non-existent at the moment and I'm not sure how good we can make it?). At least the oil burns all night :).

I guess we'll live with it for the moment, but does anyone have any other suggestions? I've been thinking of propane on-demand linked to a solar system (but that's probably the most expensive option, at least in up-front costs), or else swapping out the storage tank (when it goes) for a propane hot water heater. Can you get those with two coils in them so that I could hook up the oil stove and a solar system, and then just turn on the propane an hour or so before I wanted a shower to top up the heat? I've also read on here that propane hot water heaters are prone to backdrafting, so would it be a safety issue if I've got a woodstove in the living room? The house is ridiculously leaky at the moment, but we're hoping to reduce that at least a bit in the future.